In many cases, the more the material that needs kneading such as mortar, concrete or ground material is kneaded, the better the properties or the characteristics or physical properties thereof become. Accordingly, in case of such an object material, a sufficient kneading work will be needed.
In noticing the conventional kneading method, there are mixers (kneaders) such as an arm type, shell type, and roll type according to the kneading system. Since these kneaders perform the work mechanically, any type of them may be suitable for kneading a large amount of material.
However, although such a conventional kneader is surely effective depending on the material to be kneaded, it is known that such a kneader is not so effective when consideration is given from the standpoint of energy or time needed for kneading.
Also, since any of the mixers (kneaders) such as the arm type, shell type, and roll type which have been frequently used conventionally have mechanical parts that are movable, the wear or damage is likely to occur correspondingly. Furthermore, the apparatus itself is relatively costly. These points are remarkable particularly in the case where the mortar or concrete containing particles such as fine aggregate or coarse aggregate is used as the object material in the field of construction and civil engineering.
Therefore, in view of such problems, the applicant has already proposed the invention of the kneading method and the kneading apparatus as described in Japanese Patent Laid-Open Publication No. 9-253467. This is the technology for kneading a fluidized object material by passing it through a plurality of irregular passages having varying sectional shapes.
Namely, as shown in FIG. 7, used in this technology is a kneader body 30 in which sectional shapes of the irregular passages 1 and 2 are changed continuously from an inlet to an outlet. Then, the object material is pressurized and fed from the inlet of each irregular passage 1, 2 of this kneader body 30. As a result, the object material is layered in a stratified manner. The compression force and the shearing force are applied to the material, and then, the material is rolled and layered. Again, the compression force and the shearing force are applied to the material to repeat the rolling and layering to thereby knead and mix the material.
The kneader body 30 used here comprises a plurality of elements 31, 31 connected in series in a direction of the irregular passages 1, 2, each element 31 being provided with a plurality of irregular passages 1, 2 arranged in parallel. The inlet port of each irregular passage 1, 2 is on one end of the element 31 and the outlet port thereof is on the other end of the element 31. The adjacent elements 31 are connected in such a manner that the inlet port of the element 31 on one side intersects the outlet port of the element 31 on the other side so that the merging and dividing of the object material may be performed at the connection portion. The merging and dividing are performed by partitions 3, 4 between the irregular passages 1, 2.
An n-number of elements 31 are connected to one another so that the object material becomes stratified corresponding to the n-power of 2 at the outlet, thereby obtaining an excellent kneading efficiency. If the thirty elements 31 are connected to one another, the kneading corresponds to the kneading of as many times as about one billion (=2.sup.30) times. The connection of the elements 31 is performed by utilizing a flange F with bolt holes f1 at each end of each element.
In the case where such a kneading technology is adopted, it is possible to knead effectively the object material by applying the compression force and the shearing force, while changing the sectional shape of the object material itself. Also, the merging step and the dividing step are repeated for kneading the object material thereby the efficiency of kneading can be enhanced highly. In addition, it is possible to obtain such an advantage to omit the directly movable portions to thereby prevent the wear or damage.
The inventors of the present application have vigorously studied for further improvements of this kneading technology, and, as a result, they have found that there are still problems to be solved in the following points (1) to (3).
(1) In the kneading method in which the object material is pressurized and fed, an extremely good result may be obtained, but in the case where the idea of mixing by utilizing the gravitational force of the object material is adopted, that is, as shown in FIG. 8(a) the method in which the kneader body 30 is arranged vertically and the object material is caused to fall by the gravitational force for mixing is adopted, there is a problem particularly in the point of mixing efficiency. This is because, if the material for concrete, ground material or the like is fed as the object material, and when the material is passed through the kneader body 30, the merging and dividing are repeated for kneading as the fed material passes from above downwardly through the irregular passages 1, 2 of each element 31. However, as shown in FIGS. 8(b) to 8(e), a phenomenon occurs due to the structural feature of the elements that the material passing through plus(+) and minus(-) regions are pulled straightly through these regions, in any case. For this reason, as shown in FIG. 8(f), such a phenomenon is liable to occur that the material C after having been mixed is concentrated at plus (+) and minus (-) regions in two piles and the portion of material having a large diameter is rolled out to the lower portion of the piles.
(2) It has been found that such a phenomenon occurs similarly even in the case of kneading the concrete. Namely, it has been found that simply with the vertical arrangement, it is insufficient to apply the compression force and the shearing force to the object material and to effectively knead the material. Accordingly, in the case where the vertical arrangement utilizing the gravitational force is used, there is room for further enhancing the kneading efficiency.
(3) As a result of reviewing the causes of the above-described points (1) and (2), in detail, it is found that, as shown in FIG. 7, in the case where a plurality of elements, each including two irregular passages 1 and 2, are connected to one another, both the mixing function and the kneading function become lower than the theoretical functions. Namely, in the arrangement where the plurality of elements, each having three or four or more irregular passages, are connected to one another, almost no through-passage through which the object material is pulled straightly is formed in the kneader body 30, and the substantially theoretical functions may be obtained. Accordingly, also in the cases where the elements, each having two irregular passages, are used, it is necessary to adopt some approach, in order not to reduce the functions. In particular, this is because, in the element having the two irregular passages, the structure itself is comparatively simple and the workability is good thereby to provide a high usable property.
Note that the technology disclosed in Japanese Patent Publication No. 53-27024 (post examination publication) proposes a mixer of granular material. This is directed to an idea of arranging the mixer in a vertical direction and mixing by utilizing the fall of the granular material by the gravitational force thereof. This mixer also has the problem that the straight through-passage is formed and the above-described theoretical mixings effect could not be obtained. Of course, in the technology disclosed in this publication, there is no idea of feeding the material under pressure to apply the compression force and the shearing force for kneading.